The head of the government's spending watchdog has been cleared of wrongdoing over his £336,000 travel bill.
Sir John's expenses were in line with existing rules, the report said
National Audit Office head Sir John Bourn acted "in accordance with the existing rules on such expenditure", the Public Accounts Commission said.
But "in the light of public concern" a more transparent expenses system was needed, the commission said.
Sir John made 43 foreign trips in three years, it emerged, after a Freedom of Information request by Private Eye.
Among them were visits to the US, the Bahamas, South Africa, Brazil and New Zealand. On 22 trips he was accompanied by his wife.
The National Audit Office said the overseas visits were on official business and part of "our international work to raise global standards of accountability".
The commission said there was "no evidence of impropriety" in the use of public money, and that the expenses were "in accordance with the existing rules on such expenditure."
But it said "a more transparent system" was needed and has recommended that Sir John should be made subject to the sort of rules that apply to permanent secretaries in Whitehall.
Details of the new system are still being worked out but Sir John is understood to welcome the changes.
A former Ministry of Defence official, Sir John became the NAO's Comptroller and Auditor General in 1988.
In March 2006 he was appointed to advise ministers on potential clashes between their public duties and private affairs - and to investigate any claims that the rules have been broken.